Safer heart surgery from humble blood pressure cuff

Safer heart surgery from humble blood pressure cuff

Scientists have discovered that inflating a blood pressure cuff on the upper arm immediately prior to heart bypass surgery could decrease risk of heart injury and increase long-term survival rate.

According to the US Centers for Disease Control and Prevention (CDC), around 395,000 coronary artery bypass graft surgeries were carried out in the US in 2010.

Heart surgery, such as coronary bypass, can often cause heart muscle damage, the researchers say. It is linked to reduced long-term survival and can cause severe health outcomes such as heart attacks.

Researchers from the University School of Medicine, Essen, Germany, analyzed the effects of a procedure called remote ischemic preconditioning on 162 patients scheduled to undergo coronary artery bypass graft surgery.

A control group of 167 patients undergoing heart surgery who did not have remote ischemic preconditioning were also monitored.

Remote ischemic preconditioning is a procedure that involves temporarily cutting off the blood supply, then restoring it to an area away from the heart.

The study, published in the The Lancet, looked at whether this procedure affects long-term survival following bypass surgery, and whether it has effects on other health issues, such as stroke and heart attack.

Blood pressure cuff: blood flow of the heart bypass patients was restricted before surgery by simple use of a sphygmomanometer

The patients undergoing remote ischemic preconditioning were:

  • Anesthetized prior to surgery and had their blood flow restricted for 5 minutes with a standard blood pressure cuff, which was inflated on their upper left arm.
  • They then had their blood supply restored for 5 minutes as the cuff deflated.
  • This procedure was repeated three times.

Following the surgery, the patients' blood concentrations of a substance called troponin 1 was measured. This substance is a biomarker protein that reveals any damage to the heart muscle. A higher concentration of troponin 1 means extensive damage has occurred.

Additionally, the patients were monitored for up to 4 years after surgery in order to see whether remote ischemic preconditioning had any effects on their long-term health.

Lower risks of death

Results of the study showed that patients who had remote ischemic preconditioning had troponin 1 levels 17% lower compared with those who did not undergo the treatment 72 hours after surgery.

One year after surgery, the findings showed that:

  • Patients who had remote ischemic preconditioning were 73% less likely to have died of any cause compared with patients who did not have the treatment.
  • They were also 86% less likely to die from a stroke or heart attack.

Professor Gerd Heusch of the Institute of Pathophysiology at the University School of Medicine, says:

The results of our study are very encouraging that remote ischemic preconditioning not only reduces heart muscle injury but also improves long-term health outcomes for heart bypass patients."

Benefits 'beyond the heart'

The study authors say that it was already common knowledge that remote ischaemic preconditioning helps reduce injury to heart muscle, but they add that this study is the first randomized control trial to provide evidence that the procedure encourages longer survival in coronary bypass patients.

"The beauty of remote ischemic preconditioning is that it is non-invasive, simple, cheap, and safe," said Dr. Matthias Thielmann of the department of thoracic and cardiovascular surgery at the university.

"This procedure could be a promising and simple strategy to protect patients' heart muscle during surgery and hopefully improve health outcomes after surgery," he said.

But in a comment piece at the end of the study, Professor Michel Ovize of the Louis Pradel Hospital in France says that although this research highlights the benefits of remote ischemic preconditioning directly related to the heart, he believes the findings show the potential of possibilities beyond that.

"The incidence of non-heart-related events, such as sepsis or stroke, was lower in the remote ischemic preconditioning group than in the control group, albeit of few events overall," said Prof. Ovize.

"These findings suggest that the effect on the heart might be only one aspect of a much wider effect, and that remote conditioning, unlike local conditioning, might lead to persistent protection."

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Section Issues On Medicine: Medical practice